1. Field of the Invention
The present invention relates to a method for operating an internal combustion engine.
2. Description of Related Art
Methods are known in which individual cylinders of an internal combustion engine are diagnosed for an injection quantity error.
It is furthermore known that the legal requirements are increasing for the diagnosis of injection quantity errors or for the detection of inequalities in the air/fuel ratio of the cylinders to reduce the exhaust emissions.
A method for misfire detection and cylinder balancing in internal combustion engines having knock control is known from published German patent application document DE 100 01 274 A1. Uneven running values are ascertained and compared to a threshold value. The correction factors are ascertained based on the deviation.
An electronic control unit for controlling the internal combustion engine, the control unit having an uneven running ascertainment unit and an injection quantity correction unit, is known from published German patent application document DE 10 2006 026 390 A1. An injection quantity of a cylinder to be checked is adjusted toward “lean” in a ramp-like manner until a predefined uneven running differential value is reached. Individual differential adjustment values are successively ascertained for every cylinder, and in the presence of all differential adjustment values, a particular cylinder-individual correction value is ascertained and stored as a function of all differential adjustment values. Subsequently, the injection quantity may be corrected in a cylinder-individual manner.